/*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* Copyright (C) IBM Corporation, 2005
* Jeff Muizelaar, 2006, 2007
* Pekka Paalanen, 2008 <pq@iki.fi>
*
* Derived from the read-mod example from relay-examples by Tom Zanussi.
*/
#define pr_fmt(fmt) "mmiotrace: " fmt
#define DEBUG 1
#include <linux/module.h>
#include <linux/debugfs.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/version.h>
#include <linux/kallsyms.h>
#include <asm/pgtable.h>
#include <linux/mmiotrace.h>
#include <asm/e820.h> /* for ISA_START_ADDRESS */
#include <asm/atomic.h>
#include <linux/percpu.h>
#include <linux/cpu.h>
#include "pf_in.h"
struct trap_reason {
unsigned long addr;
unsigned long ip;
enum reason_type type;
int active_traces;
};
struct remap_trace {
struct list_head list;
struct kmmio_probe probe;
resource_size_t phys;
unsigned long id;
};
/* Accessed per-cpu. */
static DEFINE_PER_CPU(struct trap_reason, pf_reason);
static DEFINE_PER_CPU(struct mmiotrace_rw, cpu_trace);
static DEFINE_MUTEX(mmiotrace_mutex);
static DEFINE_SPINLOCK(trace_lock);
static atomic_t mmiotrace_enabled;
static LIST_HEAD(trace_list); /* struct remap_trace */
/*
* Locking in this file:
* - mmiotrace_mutex enforces enable/disable_mmiotrace() critical sections.
* - mmiotrace_enabled may be modified only when holding mmiotrace_mutex
* and trace_lock.
* - Routines depending on is_enabled() must take trace_lock.
* - trace_list users must hold trace_lock.
* - is_enabled() guarantees that mmio_trace_{rw,mapping} are allowed.
* - pre/post callbacks assume the effect of is_enabled() being true.
*/
/* module parameters */
static unsigned long filter_offset;
static int nommiotrace;
static int trace_pc;
module_param(filter_offset, ulong, 0);
module_param(nommiotrace, bool, 0);
module_param(trace_pc, bool, 0);
MODULE_PARM_DESC(filter_offset, "Start address of traced mappings.");
MODULE_PARM_DESC(nommiotrace, "Disable actual MMIO tracing.");
MODULE_PARM_DESC(trace_pc, "Record address of faulting instructions.");
static bool is_enabled(void)
{
return atomic_read(&mmiotrace_enabled);
}
static void print_pte(unsigned long address)
{
unsigned int level;
pte_t *pte = lookup_address(address, &level);
if (!pte) {
pr_err("Error in %s: no pte for page 0x%08lx\n",
__func__, address);
return;
}
if (level == PG_LEVEL_2M) {
pr_emerg("4MB pages are not currently supported: 0x%08lx\n",
address);
BUG();
}
pr_info("pte for 0x%lx: 0x%llx 0x%llx\n",
address,
(unsigned long long)pte_val(*pte),
(unsigned long long)pte_val(*pte) & _PAGE_PRESENT);
}
/*
* For some reason the pre/post pairs have been called in an
* unmatched order. Report and die.
*/
static void die_kmmio_nesting_error(struct pt_regs *regs, unsigned long addr)
{
const struct trap_reason *my_reason = &get_cpu_var(pf_reason);
pr_emerg("unexpected fault for address: 0x%08lx, last fault for address: 0x%08lx\n",
addr, my_reason->addr);
print_pte(addr);
print_symbol(KERN_EMERG "faulting IP is at %s\n", regs->ip);
print_symbol(KERN_EMERG "last faulting IP was at %s\n", my_reason->ip);
#ifdef __i386__
pr_emerg("eax: %08lx ebx: %08lx ecx: %08lx edx: %08lx\n",
regs->ax, regs->bx, regs->cx, regs->dx);
pr_emerg("esi: %08lx edi: %08lx ebp: %08lx esp: %08lx\n",
regs->si, regs->di, regs->bp, regs->sp);
#else
pr_emerg("rax: %016lx rcx: %016lx rdx: %016lx\n",
regs->ax, regs->cx, regs->dx);
pr_emerg("rsi: %016lx rdi: %016lx rbp: %016lx rsp: %016lx\n",
regs->si, regs->di, regs->bp, regs->sp);
#endif
put_cpu_var(pf_reason);
BUG();
}
static void pre(struct kmmio_probe *p, struct pt_regs *regs,
unsigned long addr)
{
struct trap_reason *my_reason = &get_cpu_var(pf_reason);
struct mmiotrace_rw *my_trace = &get_cpu_var(cpu_trace);
const unsigned long instptr = instruction_pointer(regs);
const enum reason_type type = get_ins_type(instptr);
struct remap_trace *trace = p->private;
/* it doesn't make sense to have more than one active trace per cpu */
if (my_reason->active_traces)
die_kmmio_nesting_error(regs, addr);
else
my_reason->active_traces++;
my_reason->type = type;
my_reason->addr = addr;
my_reason->ip = instptr;
my_trace->phys = addr - trace->probe.addr + trace->phys;
my_trace->map_id = trace->id;
/*
* Only record the program counter when requested.
* It may taint clean-room reverse engineering.
*/
if (trace_pc)
my_trace->pc = instptr;
else
my_trace->pc = 0;
/*
* XXX: the timestamp recorded will be *after* the tracing has been
* done, not at the time we hit the instruction. SMP implications
* on event ordering?
*/
switch (type) {
case REG_READ:
my_trace->opcode = MMIO_READ;
my_trace->width = get_ins_mem_width(instptr);
break;
case REG_WRITE:
my_trace->opcode = MMIO_WRITE;
my_trace->width = get_ins_mem_width(instptr);
my_trace->value = get_ins_reg_val(instptr, regs);
break;
case IMM_WRITE:
my_trace->opcode = MMIO_WRITE;
my_trace->width = get_ins_mem_width(instptr);
my_trace->value = get_ins_imm_val(instptr);
break;
default:
{
unsigned char *ip = (unsigned char *)instptr;
my_trace->opcode = MMIO_UNKNOWN_OP;
my_trace->width = 0;
my_trace->value = (*ip) << 16 | *(ip + 1) << 8 |
*(ip + 2);
}
}
put_cpu_var(cpu_trace);
put_cpu_var(pf_reason);
}
static void post(struct kmmio_probe *p, unsigned long condition,
struct pt_regs *regs)
{
struct trap_reason *my_reason = &get_cpu_var(pf_reason);
struct mmiotrace_rw *my_trace = &get_cpu_var(cpu_trace);
/* this should always return the active_trace count to 0 */
my_reason->active_traces--;
if (my_reason->active_traces) {
pr_emerg("unexpected post handler");
BUG();
}
switch (my_reason->type) {
case REG_READ:
my_trace->value = get_ins_reg_val(my_reason->ip, regs);
break;
default:
break;
}
mmio_trace_rw(my_trace);
put_cpu_var(cpu_trace);
put_cpu_var(pf_reason);
}
static void ioremap_trace_core(resource_size_t offset, unsigned long size,
void __iomem *addr)
{
static atomic_t next_id;
struct remap_trace *trace = kmalloc(sizeof(*trace), GFP_KERNEL);
/* These are page-unaligned. */
struct mmiotrace_map map = {
.phys = offset,
.virt = (unsigned long)addr,
.len = size,
.opcode = MMIO_PROBE
};
if (!trace) {
pr_err("kmalloc failed in ioremap\n");
return;
}
*trace = (struct remap_trace) {
.probe = {
.addr = (unsigned long)addr,
.len = size,
.pre_handler = pre,
.post_handler = post,
.private = trace
},
.phys = offset,
.id = atomic_inc_return(&next_id)
};
map.map_id = trace->id;
spin_lock_irq(&trace_lock);
if (!is_enabled()) {
kfree(trace);
goto not_enabled;
}
mmio_trace_mapping(&map);
list_add_tail(&trace->list, &trace_list);
if (!nommiotrace)
register_kmmio_probe(&trace->probe);
not_enabled:
spin_unlock_irq(&trace_lock);
}
void mmiotrace_ioremap(resource_size_t offset, unsigned long size,
void __iomem *addr)
{
if (!is_enabled()) /* recheck and proper locking in *_core() */
return;
pr_debug("ioremap_*(0x%llx, 0x%lx) = %p\n",
(unsigned long long)offset, size, addr);
if ((filter_offset) && (offset != filter_offset))
return;
ioremap_trace_core(offset, size, addr);
}
static void iounmap_trace_core(volatile void __iomem *addr)
{
struct mmiotrace_map map = {
.phys = 0,
.virt = (unsigned long)addr,
.len = 0,
.opcode = MMIO_UNPROBE
};
struct remap_trace *trace;
struct remap_trace *tmp;
struct remap_trace *found_trace = NULL;
pr_debug("Unmapping %p.\n", addr);
spin_lock_irq(&trace_lock);
if (!is_enabled())
goto not_enabled;
list_for_each_entry_safe(trace, tmp, &trace_list, list) {
if ((unsigned long)addr == trace->probe.addr) {
if (!nommiotrace)
unregister_kmmio_probe(&trace->probe);
list_del(&trace->list);
found_trace = trace;
break;
}
}
map.map_id = (found_trace) ? found_trace->id : -1;
mmio_trace_mapping(&map);
not_enabled:
spin_unlock_irq(&trace_lock);
if (found_trace) {
synchronize_rcu(); /* unregister_kmmio_probe() requirement */
kfree(found_trace);
}
}
void mmiotrace_iounmap(volatile void __iomem *addr)
{
might_sleep();
if (is_enabled()) /* recheck and proper locking in *_core() */
iounmap_trace_core(addr);
}
int mmiotrace_printk(const char *fmt, ...)
{
int ret = 0;
va_list args;
unsigned long flags;
va_start(args, fmt);
spin_lock_irqsave(&trace_lock, flags);
if (is_enabled())
ret = mmio_trace_printk(fmt, args);
spin_unlock_irqrestore(&trace_lock, flags);
va_end(args);
return ret;
}
EXPORT_SYMBOL(mmiotrace_printk);
static void clear_trace_list(void)
{
struct remap_trace *trace;
struct remap_trace *tmp;
/*
* No locking required, because the caller ensures we are in a
* critical section via mutex, and is_enabled() is false,
* i.e. nothing can traverse or modify this list.
* Caller also ensures is_enabled() cannot change.
*/
list_for_each_entry(trace, &trace_list, list) {
pr_notice("purging non-iounmapped trace @0x%08lx, size 0x%lx.\n",
trace->probe.addr, trace->probe.len);
if (!nommiotrace)
unregister_kmmio_probe(&trace->probe);
}
synchronize_rcu(); /* unregister_kmmio_probe() requirement */
list_for_each_entry_safe(trace, tmp, &trace_list, list) {
list_del(&trace->list);
kfree(trace);
}
}
#ifdef CONFIG_HOTPLUG_CPU
static cpumask_var_t downed_cpus;
static void enter_uniprocessor(void)
{
int cpu;
int err;
if (downed_cpus == NULL &&
!alloc_cpumask_var(&downed_cpus, GFP_KERNEL)) {
pr_notice("Failed to allocate mask\n");
goto out;
}
get_online_cpus();
cpumask_copy(downed_cpus, cpu_online_mask);
cpumask_clear_cpu(cpumask_first(cpu_online_mask), downed_cpus);
if (num_online_cpus() > 1)
pr_notice("Disabling non-boot CPUs...\n");
put_online_cpus();
for_each_cpu(cpu, downed_cpus) {
err = cpu_down(cpu);
if (!err)
pr_info("CPU%d is down.\n", cpu);
else
pr_err("Error taking CPU%d down: %d\n", cpu, err);
}
out:
if (num_online_cpus() > 1)
pr_warning("multiple CPUs still online, may miss events.\n");
}
/* __ref because leave_uniprocessor calls cpu_up which is __cpuinit,
but this whole function is ifdefed CONFIG_HOTPLUG_CPU */
static void __ref leave_uniprocessor(void)
{
int cpu;
int err;
if (downed_cpus == NULL || cpumask_weight(downed_cpus) == 0)
return;
pr_notice("Re-enabling CPUs...\n");
for_each_cpu(cpu, downed_cpus) {
err = cpu_up(cpu);
if (!err)
pr_info("enabled CPU%d.\n", cpu);
else
pr_err("cannot re-enable CPU%d: %d\n", cpu, err);
}
}
#else /* !CONFIG_HOTPLUG_CPU */
static void enter_uniprocessor(void)
{
if (num_online_cpus() > 1)
pr_warning("multiple CPUs are online, may miss events. "
"Suggest booting with maxcpus=1 kernel argument.\n");
}
static void leave_uniprocessor(void)
{
}
#endif
void enable_mmiotrace(void)
{
mutex_lock(&mmiotrace_mutex);
if (is_enabled())
goto out;
if (nommiotrace)
pr_info("MMIO tracing disabled.\n");
kmmio_init();
enter_uniprocessor();
spin_lock_irq(&trace_lock);
atomic_inc(&mmiotrace_enabled);
spin_unlock_irq(&trace_lock);
pr_info("enabled.\n");
out:
mutex_unlock(&mmiotrace_mutex);
}
void disable_mmiotrace(void)
{
mutex_lock(&mmiotrace_mutex);
if (!is_enabled())
goto out;
spin_lock_irq(&trace_lock);
atomic_dec(&mmiotrace_enabled);
BUG_ON(is_enabled());
spin_unlock_irq(&trace_lock);
clear_trace_list(); /* guarantees: no more kmmio callbacks */
leave_uniprocessor();
kmmio_cleanup();
pr_info("disabled.\n");
out:
mutex_unlock(&mmiotrace_mutex);
}
